This invention relates to mounting means for fluid pressure transmitters in fluid communication with a main flow line, and more particularly to a common mounting means for both a differential pressure transmitter and a gauge pressure transmitter.
Normally, a flow restriction is placed in a main flow line transporting a fluid and pressure taps are made on each side of the restriction for obtaining high and low fluid pressures. Such a flow restriction may comprise an orifice plate, flow nozzle, or venturi tube, for example. The high and low pressures taken from opposed sides of the restriction in the main flow line are communicated to a transmitter for measuring and transmitting the measured pressure or pressure differential by a suitable electronic signal or the like to a remote location, such as a control room, where the pressure or pressure differential may be monitored and/or recorded by an operator.
Gas flow measurements in a main flow line across a reduced diameter orifice require several variable inputs including the differential pressure and the gauge or static pressure. A separate installation has normally been provided for each of the pressure transmitters with each installation normally utilizing a pair of orifice taps or ports one on each side of the reduced installation normally utilizing a pair of orifice laps or ports one on each side of the reduced diameter orifice. The use of two separate installations for flow measurement through a main flow line increases the possibility of malfunction from possible leakage at the connecting joints or improper installation, as well as requiring a relatively large amount of space for the two installations.
A manifold is normally mounted between the main flow line and the pressure transmitters. The manifold permits blocking or venting of the pressure lines to the transmitters which may be required for proper calibration of the transmitters. While a single installation from the main flow line has been used heretofore for a differential pressure transmitter and a gauge pressure transmitter, the transmitters have been mounted on separate sides of the manifold or have been mounted in a series relation to each other with the gauge pressure transmitter being downstream from the differential pressure transmitter. Such an arrangement sometimes makes it difficult for "rodding" or cleaning through passages and valve seats, and usually requires utilization of he manifold for calibration of the transmitters.